Various prior devices have been proposed for cleaning the shoes of a person stepping or standing on the device at the entrance to a building, and all such devices of which I am aware have had certain disadvantages in respect to the construction and movement of the brush elements that perform the cleaning, and the construction and arrangement of the plate elements which surround the brushes and support the weight of the person stepping onto the machine.
U.S. Pat. No. 2,647,241 shows a mechanical floor mat having an open grid formed by spaced metal strips between which rows of bristle tufts are reciprocated by rack and pinion means to provide the cleaning action. The bristle tufts are described as secured in recesses in the metal shafts, which would not be a satisfactory or durable construction as the tufts would tend to come loose in continued use. Furthermore, if any of the bristle tufts become worn or fall out, the entire bar must be replaced. Moreover, the narrow strips forming the grid are widely spaced apart, as are the bristle tufts, so that a person standing on the grid does not have a stable support, particularly when wearing the high narrow heels prevalent in women's shoes.
These same disadvantages, together with others, are present in the shoe cleaning devices of prior U.S. Pat. Nos. 2,649,599 and 3,029,452. Other known prior devices have banks of bristles which are reciprocated in a horizontal plane while contacting the entire surfaces of the shoe soles of a person standing or stepping thereon, thereby providing an extremely unstable support.